After Enterprise NX-01 entered the Delphic Expanse, members of the Xindi Council wanted to attack the ship because they believed that it was the first ship of an invasion force. Degra was against attacking the vessel, feeling that such an action could reveal the Xindi and their presence. Degra believed that it was best to keep hidden until the new weapon was complete. He was able to persuade the council to follow this course of action. (ENT: "The Xindi")

Degra's work on the Xindi weapon took years. It was too slow to progress for the Council at times; after an accident in his laboratory, the Council went so far as to consider dropping his project in favor of a bio-weapon. Degra insisted that they did not have enough information about Humananatomy to make a bio-weapon. The Reptilians brought in Rajiin, who was able to provide the Council with biometric scans she took on Enterprise. With this new information, the Xindi had the information needed for a bio-weapon. In October of 2153, Degra visited a Xindi-Arboreal colony to acquire some kemocite for his weapon. Jonathan Archer had convinced Gralik, the Xindi in charge of the processing center, to sabotage the kemocite, which caused further delays in completing the weapon. (ENT: "Rajiin", "The Shipment")

Later, Degra conducted a test that not only ended up being below expectations, but also lost the prototype weapon. He tested the prototype in the Calindra system. When the weapon was launched, its power was immense, but the power was unstable and it did not completely destroy the planet. When Enterprise attempted to capture the weapon, Degra ordered all the defending ships to attack, not realizing that the Andorians, who ultimately managed to capture the prototype weapon, were assisting the Humans. (ENT: "Proving Ground")

Degra was captured by Enterprise after the failed test, and Archer was able to trick him into revealing the location of the weapon. He led Degra to believe that they were three years in the future. Degra also believed that the Xindi had destroyed Earth, but that the victory had led to a civil war among the various Xindi species. He was furthermore fooled into believing he had been imprisoned with Archer in an Insectoid prison. Degra then revealed that the weapon was at Azati Prime. However, he caught on to Archer's ruse and tried to attack him. Degra later inadvertently confirmed that Azati Prime was the weapon site, shouting at Archer, "You'll never get close to the weapon! Our defense perimeter will destroy you!" Afterwards, his and his colleagues' memories were then wiped clean and Degra was returned to his own ship along with his assistants. (ENT: "Stratagem")

In the final draft script of "Stratagem", Degra did not directly confirm, at the end of the episode, that the weapon was at Azati Prime. Instead, he merely shouted, "You'll never make it through the defense perimeter... they'll destroy you!" However, a subsequent scene description referred to Degra as indeed having inadvertently confirmed for Archer that the weapon was being built at Azati Prime.

Degra felt immensely guilty that he had caused the attack on Earth that killed over seven million people, most of whom had been innocents and children. As he worked on the final weapon, he kept on reassuring himself that destroying Earth would save his own people. After Archer was captured by the Reptilians, he demanded to talk to Degra. Degra arrived and listened to Archer, who told him that deploying the Xindi weapon would lead to the extinction of both their species, and that the Sphere-Builders were manipulating the Xindi. Degra began to believe Archer and insisted that the Reptilians call off the attack on Enterprise. When they refused, Degra persuaded the Council to order a halt to the attack. (ENT: "Azati Prime")

Degra was the first Xindi Council member to trust Archer; he was swayed by evidence Archer presented showing that the Guardians were lying to the Xindi. Degra met with Archer aboard Enterprise, and was shown the corpses of the Reptilians who Archer had followed into the past and prevented building a bio-weapon. He also showed Degra the body of one of the Sphere-Builder species who served as a test subject. Degra was shown data that proved that the spheres were changing space so that the Sphere-Builders could inhabit the region. When a Reptilian ship approached Enterprise and Degra's ship, Degra helped destroy the Reptilian ship. He arranged for Archer to present his case to the Xindi Council in February of 2154. (ENT: "The Forgotten", "The Council")

Dolim stabs Degra

After Archer spoke to the Council with Degra's support, the Xindi reconsidered their attack on Earth. Dolim pretended to be swayed to Degra's side, but turned out to be deceiving him; Dolim murdered Degra in retribution for Degra's destruction of the Reptilian ship. As Degra was dying, Dolim promised to find and kill Degra's wife and children as well. Dolim, however, was unable to carry out his threat, as he was killed by Archer, who was attempting to stop Dolim from destroying Earth. (ENT: "The Council", "Zero Hour")

Conceptually, the initial inspiration for the character of Degra was J. Robert Oppenheimer. Executive Producer Brannon Braga explained, "We knew we wanted to create an Oppenheimer-like character who was the mastermind behind building the bomb, who was very committed to his species but wracked with guilt, just like Oppenheimer. We always knew we wanted to do it." (Star Trek Magazine issue 117, p. 62; Star Trek Encyclopedia (4th ed., vol. 1, p. 197) Observing another facet that Degra shared with Oppenheimer, Braga noted, "He killed millions of people." (Star Trek: Communicator issue 151, p. 31)

When Degra was introduced in the script of "The Xindi", he was referred to as "a severe-looking male in his 50's."

Randy Oglesby took some clues about Degra from a scene he was asked to read upon auditioning for the role. "The material I auditioned with, I never actually performed on the show," the actor related. "Evidently it was just something that was created for the sake of the audition. In terms of the character, it was almost the essence of his story. I always imagined the audition scene took place in a laboratory. Somebody comes in and asks me something about building this weapon. I say, 'All right. We are building a weapon, but do you realize what we are going to be doing with this weapon?' I confront this other character with the moral dilemma that was the meat and potatoes of my character." (Star Trek: Communicator issue 151, p. 49)

Indeed, although Randy Oglesby was initially told – shortly after landing the role – that the character merely might be recurring, the dilemma central to Degra's persona was expanded on by the writers as ENT Season 3 progressed, forcing him to contemplate his place in the conflict between the Humans and the Xindi. (Star Trek: Communicator issue 151, p. 49) This was spurred on by Oglesby's performances in the part. Brannon Braga remarked, "We found a great actor [....] Randy gave us more than we ever expected, so we used the character more than we thought we would. Hopefully the audience got interested in him." Braga himself believed the character, as a whole, "worked." (Star Trek Magazine issue 117, p. 62) Oglesby had similar feelings and, shortly after playing the role, he commented, "The way they have written the character has been very true to their conception, to the writers' credit [....] There are just so many nice little personal touches that went along with the character [....] It was one of the high points of my work, getting to do this big part in such an interesting story. That's the bottom line for me." (Star Trek: Communicator issue 151, pp. 49 & 50)

In the final draft script of "Stratagem", Degra was at first described thus; "His appearance is very different from when we saw him in the previous episode, "Proving Ground". Degra looks haggard... his hair has grayed slightly." In the same scripted scene, Degra was said to have "a few days' beard growth," though this doesn't match Degra's appearance in the final version of that installment.

At which point the concept of Degra's murder was thought up is debatable. In one interview, Brannon Braga claimed, "We didn't necessarily know we were going to kill Degra; that came as the season went on." (Star Trek Magazine issue 117, p. 62) In a separate interview, Braga stated, "You've got to take Degra away [via murder]. We always knew we would do it." (Star Trek Magazine issue 151, p. 34) Randy Oglesby had long-held suspicions that Degra would be killed. "There was kind of an inevitability to it that I love," he observed. "My character is making these choices. I had a feeling he was going to have to die; I had a feeling he was going to be the sacrificial lamb." (Star Trek: Communicator issue 151, p. 50) Alternatively, Braga – who ultimately liked the death of Degra – considered, "I think they [the audience] were kind of surprised that he got murdered before the season ended." (Star Trek Magazine issue 117, p. 62)